Brake system



G. L. SMITH BRAKE SYSTEM Sept. 16, 1930.

Filed larch 27, 1928 LVJ awuem boa 6602:9611 .Jmifig Patented Sept. 16,1930 UNITED STATES PATENT iOFF'l CEr,

J GEORGE L. SMITH, OF WASHINGTON, DISTRICT .OF COLUMBIA, ASSIGNOR TOUNITED STATES ORDNANCE' COMPANY, OF 'WASHINGTON, DISTRICT OF COLUMBIA,A. COR- IPORATION OF VIRGINIA" BRAKE SYSTEM Application filed March 27,1928. Serial no, 265,040.

My invention relates to brake systems for motor vehicles andparticularly that type adapted to simultaneously apply a retarding forceeither directly or indirectly to the front and rear wheels of'suchvehicle.

constructed with, resultant economy in pro-.

Generally speaking it is the purpose of my invention to provide a brake.system of the type specified which will eliminate a large number of theparts of such systems as now duction and installation; and which willgive great braking power with safety under all.

operating conditions which may be encountered.

The conventional design of motor vehicles permits the use of a brake onthe. propeller shaft for braking the vehicle through the 'rear wheels,but the use of sucha brake has been heretofore avoided owing tothe'additional stresses imposed thereby on the drive mechanism betweenthe engine and rear wheels. My invention contemplates the use of a brakeon the propeller shaft of an automobile; but in association with novelfeatures of construction and arrangement which serve to reduce theaforementioned stresses to a point well below'those produced by theengine so that such a brake can be used with safety and thus enable meto attain a material reduction in the production cost of motor vehiclesequipped with brake systems of the general type specified, by theelimination from such systems of rear wheel brakes and their operatingconnections.

In carrying my invention into practice I.

combine front wheel brakes with a propeller 4 shaft ortransmission'brake, and by a peculiar and novel method of controlproduce a brake system capable of producing powerful braking' underthose conditions where powerful braking action is needed and safebraking under those conditions where excessive braking action cannot beused, such as on slippery pavement.

It is well known that the weight supported by the frontand 'rear axlesof a motor vehicle varies with the severity of the. retarding forceimposed bybrake application during vehicle travel. As a result of theimposi-: tion of such retarding force during vehicle travel weight isremoved from the rear axle of the vehicle and transferred to the frontaxle. The amount of weight transferred from the rear axle to the frontaxle under the conditions specified is proportional to the retardingforce and is readily computable.

As the weight carried by the axles of a motor vehicle controls thepressure of the wheel tires onthe road and as this pressure controls theamount of braking force which "the tirscan deliver to the-road, it isevident that, if proper, efi'icient and safe braking is v to be attainedduring vehicle travel, means must be provided for varying the front andf rear brake forces of the brake system. In other words as the weight iseased off the rear axle and wheels and shifted to the front axle andwheels by the retarding force incident to brake application duringvehicle travel, the

brake force should be eased off the rear of the brake system and builtup in thefront thereof, to thereby prevent the rear wheels locking longprior to the front wheels being subjected to a brake force sufficient toeffect their looking, with needless sacrifice of brake power resulting.Myinvention therefore, also contemplates the provision in a brake systemof the type specified, of means for varying the relative power of thefront and rear brakes while the brakes are in operation and by combiningsuch means with front wheel brakes and a transmission brake I'producethe equivalent of a four wheel brake system wherein the re-' tarding.forcesdeliveredto the road surface by each of the several wheel tiresis approxi- 'mately proportional" to the tire pressure on such surface,so that danger of lockinga wheel by braking is reduced while at the samestresses on the drive mechanism are reduced well below those produced bythe engine and "danger of failure or excessive wear of such viouslystated gives mechanism is avoided.

i To further explain why my device as presafe braking under cond1t1onswhere excessive braking action cannot be used, such as on slipperypavement, it is slippery hill at a" constant speed as much bettercontrol of the vehicle would be obtained.

To further reduce possible danger of losing brake power in my improvedsystem and to comply with legal requirements specifying two separatesetsof brakes I employ afhand lever cooperatively associated with thetransmission brake and operable not only to brake the vehicle in case ofemergency, but also operable to tighten the transmission brake so that,should the driver find the permissible movement of thebrake foot pedalineffective to properly service the brakes, he could evercome thiscondition while driving the vehicle I by pulling up the hand lever todirectly tighten the transmission brake and to cause the front brakes insubsequent operation to tighten up as the brake pedal is depressed andthus restore proper service braking until such time as he has theopportunity to adjust the entire brake system. This restoration ofproper service braking,under the conditions, speciwfied, constitutes oneof the safety elements of my improved brake system.

, In the drawings chosen to illustrate my invention, thescope whereof isset forth in the appended claims- .Fig. 1 is a side elevation of a brakesystem constructed in accordance with my invention; and

i Fig. 2, a rear view thereof.

Referring to the drawing, 10 denotes the foot brake pedal of a motorvehicle mounted on a pivot 11. To the short .arm 12 of the pedal 10is'pivoted an equalizer bar 13 having a downwardly directed extension13, the free end of which carries an inertia weight 42.

A transmission brake 1 5 is mounted onthe propeller shaft 16 and iscomposed of a brake 5 band 17, brake lever 18, tension bolt ;19,adjusting nut 20, and anchor 21. An operating shaft 22 forthistransmission brake is mounted on an associated vehicle by means of endbearings 23 and 24 and attached thereto is a lever 25 which is connectedto the brake lever 18 by a link 26 so that clockwise rotation of shaft22 (Fig. 1) will pull on link 26 and apply the transmission brake. Thelever 28 keyed to the shaft 22 ,is connected to the yoke 13 by so thatthe brake power of.

the pull rod 29, so that depression of pedal 10 sets the transmissionbrake. An operating shaft 30 for front wheel brakes is mounted on anassociated vehicle by means of the bearings 31 and 32. This shaftcarries downwardly extending levers 33 at'its ends from which the brakepull rods 34 extendforward to the front wheel brakes A. -A lever 35 iskeyed to this shaft 30 about in line with lever 28 and connectionbetween lever 35 and yoke 13 is made by the pull rod 36, so that de ression of pedal 10 will likewise set the front wheel brakes. i

The mechanism heretofore described operates as follows Depression of thepedal 10 pulls on both rods 29 and 36, the pull of each rod being suchas to generate brake forces for front and rear wheels proportional tothe weight carried by these wheels when car is at rest. When the car isslowed down bythe brakes during vehicle travel the retardation causesthe weight 42 on extension 13' to swing forward,increasing the pull onrod 36'and decreasing the pull on rod 29. This increases in turn theforce of the front brakes and decreases that of the transmission brakein pro 7 portion as the transfer of car weight from rear axle and wheelsto front axle and wheels takes place.

My invention further embodies an emergency brake lever 27 pivoted in theusual manner at 43 and connected at its lower end with a link 44. Therear end of this link connects with the cam lever 45. This cam lever/l5is pivotally carried by the brake adjusting nut 20 and has a cam surface46 to force one end of the band 17 towards the lever 18 the same I aswould be the case when nut 20 is screwed up, said nut being, adjustableby disconnecting link 44 from lever 45 andutilizing lever 45 in lieu ofa wrench to rotate said nut. To assure-safe braking should any arts fromlink 26 up topedal 10 be broken i backstop 47 for lever 18. to reactagainst so. that the brake 17 can be set by hand lever 27. Thisconstruction not only gives twoindependent connections to the brake '17,but also permits the driver to get the equivalent of a provide a brakeadjustment by pulling back the hand lever a notch or two on the ratchetarc- 48. As this can' be done while car. is in motion it is thereforepossible to tighten or adjust the brakes while driving and avoid dangerof accldent due to insuflicient brake action; The brake stop 47 providedto permit ositive' setting of the transmission brake 1 7 by.

the hand lever 27 also permits the use of thishand lever in cases ofemergency to neutralize l the action. of the inertia weight 42 asfollows :If both pedal 10 and handlever 27 are operated at the same timethe eifect of a each would be to set all brakesin the-pro-' portioncontrolled by the weight 42 until hand lever were pulled back far enoughto fcrce lever 18 against the stop 47. (After this point is reachedfurther pull on hand lever would increase power of transmission brakeindependently of that of front brakes and 'the action of inertia weightwould be cut out of the system. J

To summarize the action of my system I provide first an automatic'meansof varying the front and rear brake forces so that when the vehicle isslowed down 'by brake'action swing forward slightly whenlever 10 isdepressedand thus tighten up front brakes also. Should the entirehook-up back to brake lever 18 be placed out of operation the brake 17could still' be set by the h-and lever 27.

The subject matter 'of this application which relates to a multiplebrake operating system as distinguished from a four wheel divisionalapplication filed October 8, 1929, Serial No. 398,182.

I claim: a

1. In a brake system for motor vehicles, a front wheel brake device, arear wheel'brake .device, a weighted leverconnecting said devices, andbrake applying means connected to said lever at a point.between thepoints of attachment of the brake devices, the center of gravityof saidlever being located below the point of connection thereof to the fromwheel brake device. a

2. A brake system comprisingbrakes for applying retarding forces to thefront and rear'pairs of wheels respectively of a vehicle, a brakeapplying device common to said brakes, and means operable automaticallyto impart brake applying forces to said brakes in excess of'theforcesimparted to them by said device and to vary the ratio between theforces imparted to the respective brakes.

3. A brake system comprising brakes for applying retarding forces to thefront and rear palrs of wheels respectively of a vehicle,

a brake applying device common to said brakes, and means operable byretardation of vehicle movement to impart brake applying forces to saidbrakes in excess of the forces imparted to them by said device and tovary the ratio between the forces imparted to the respective brakes.

4. A brake system comprising brakes forapplying retarding forces to thefr'ontand applying forces to said brakes in excess of the forcesimparted to them by said device and to maintain the valpe of the forcesapplied to' said brakes proportional to the weight carried by the frontand rear pairs of wheels while said forces are controlling movement ofthe vehicle,

5. A brake system comprising brakes for 'applying retarding forces tothe front and rear pairs of wheels respectively of a vehicle,

a brake applying device common to said brakes, and means operableautomatically to impart brake applying forces to said brakes in excessof'the forces imparted to them by said device and to maintain the valueof the forces applied to said brakes proportional to the weight carriedby the front and rear pairs of wheels while said forces are controllingmovement of the vehicle.

6. A brake system comprising brakes for applying retarding forces to thefront and ss ,rear pairs of wheels respectively of a vehicle, a brakeapplying device common to said brakes, and means operable by retardationof vehicle movement incident to brake application to impartbrakeapplying forces to said brakes in excess of the forces imparted to Athem by said device and to maintain the value braking system is coveredby the claims of a" of the forces applied to said brakes propor- Vtional to the weight carried by the front and rear pairs of wheels whilesaid forces are controlling movement of the vehicle.

7. A brake system for vehicles comprising a front wheel brake, a rearwheel brake, a lever, a connecting element between each brake and saidlever, said elements being attached to saidlever at spaced pointsrespectively, a

each brake and said lever, said elements being X attached to said leverat spaced points respectively, a brake applying'device pivotallyconnected to said lever at a point between the points of attachment ofsaid connecting elements therewith, the connecting element between thefront wheel brakeand said'lever being attached to said lever at a pointbetween the center of gravity of said lever and the point of attachmentthereto" of the connecting element to the rear wheel brake.-

In testimony whereof I hereunto aifix my signature.

' GEORGE L. SMITH.-

